Janković told the press on Monday that he would definitely attend the congress as a party member, but refused to say whether he would also stand for president after speculations surfaced that he would not run for party presidency.

A date for the congress is yet to be set by the PS executive committee, but it is clear that if Janković takes over the party, the ruling coalition would most likely collapse, as neither coalition partner wants to cooperate with Janković.

Janković was forced to resign as PS president last year after the Corruption Prevention Commission established that he could not account for around EUR 2m in his assets. Breach of integrity legislation was also established for the then PM Janez Janša, which resulted in the collapse of the government.

At today's press conference which he called to talk about current political developments, Janković also criticized one of the coalition partner leaders, Interior Minister Gregor Virant, who survived a second ouster motion on Friday.

Janković is certain that Virant, the head of the coalition Citizens's List (DL), lied about the purchase of cheap tickets from flag carrier Adria Airways, which was one of the main reproaches voiced against him by the opposition. A liar cannot be interior minister, said Janković.

The Ljubljana mayor added that the audio recording of Virant's testimony in front of the Commission for the Prevention of Corruption in the airfares investigation will become public this month. If the recording shows that Virant indeed lied, he should be ousted, said Janković.

Virant and Karl Erjavec, the head of coalition Pensioners' Party (DeSUS), expressed strong aversion to cooperate with Janković last year after the anti-graft watchdog found he violated anti-graft legislation and Janković stepped down as PS president to allow the formation of a government coalition under Bratušek.

Tensions have been increasing in the party for a while and the party initially planned to hold an electoral congress in October 2013. The event was postponed, as the potential victory of Janković would mean the end of the government coalition.

The ouster vote against Virant displayed the tensions within the party again, as four PS members voted against the minister despite the fact that the coalition parties included in their agreement a provision that ouster motions against government ministers are not supported by coalition partners.